ION-ACCELERATION AND ANOMALOUS TRANSPORT IN THE NEAR WAKE OF A PLASMALIMITER

Ion acceleration and anomalous transport were studied experimentally i n the near wake region of an electrically floating disk limiter immers ed in two different types of collisionless, supersonically flowing, ma gnetized plasmas: the first initially quiescent, the second initially turbulent. Ion densities and velocity distributions were obtained usin g a nonperturbing laser induced fluorescence diagnostic. Large-amplitu de, low-frequency turbulence was observed at the obstacle edge and in the wake. Rapid ion and electron configuration space transport and ion velocity space transport were observed. Configuration space and veloc ity space transport were similar for both quiescent and turbulent plas ma-obstacle systems, suggesting that plasma-obstacle effects outweigh the effects of initial plasma turbulence levels. (C) 1997 American Ins titute of Physics.